Substructural investigations, Raman, and FTIR spectroscopies of nanocrystalline ZnO films deposited by pulsed spray pyrolysis

Abstract

Nanocrystalline ZnO films were deposited on to glass substrates in the temperature range of 473–673Kusing pulsed spray pyrolysis. The structural, substructural, and optical properties of the films were investigated bymeans of X-ray diffraction analysis, Raman scattering, and Fourier transform infrared (FTIR) spectroscopy. The effect of the substrate temperature (Ts) on the coherent scattering domain (CSD) sizes L, microstrains e, andmicrostress s grades, and the average density of dislocations r in the films were estimated through the broadening of X-ray lines using the Cauchy and Gauss approximations and the threefold function convolution method. The ZnO films grown at Ts¼623–673K possessed the highest values of L, and the lowest of e, s, and r, indicating high-crystalline quality. The Raman spectra showed peaks located at 95–98, 333–336, 415, 439–442, 572, and 578– 584 cm 1, which were interpreted as E2 low(Zn), (E2 high E2 low), E1(TO), E2 high(O), A1(LO) and E1(LO) phonon modes of the ZnO wurtzite phase. The FTIR spectra showed relatively weak signals at 856, 1405, and 1560 cm 1, corresponding to the C–H and C–O stretching modes, in addition to the main Zn–O mode at 475cm 1, indicating a low content of precursor residues.